Method for setting up a WebRTC session

ABSTRACT

Some embodiments relate to a method implemented by a first terminal for setting up a session with a second terminal. An identifier of a session server is obtained at least from a subscriber device in the first terminal which comprises a subscriber identifier and an operator identifier. A session request and an identifier of the second terminal are sent to the server. At least one instruction is received from the server and a message comprising a first set, relative to the first terminal, of at least one characteristic parameter of the requested session is generated in accordance with at least one instruction received and sent to the server. A message is received from the server comprising a second set of at least one characteristic parameter of the requested session, the second set relating to the second terminal and having a non-zero overlap with the first set.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/741,417, entitled “METHOD FOR SETTING UP A WebRTC SESSION” filed Jan.13, 2020, which is a continuation of U.S. patent application Ser. No.15/317,896, entitled “METHOD FOR SETTING UP A WebRTC SESSION” filed Dec.9, 2016, and issued on Jan. 14, 2020 as U.S. Pat. No. 10,536,489, whichis the U.S. National Phase of Application No. PCT/FR2015/051468 entitled“METHOD FOR SETTING UP A WebRTC SESSION” filed Jun. 3, 2015, whichdesignated the United States, and which claims the benefit of FrenchApplication No. 1455262 filed Jun. 10, 2014.

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND Technical Field

The patent application is in the field of electronic communicationsusing mobile terminals, and more particularly in the field of WebRTCcommunications (Web Real-Time Communication).

State of the Art

With WebRTC technology, a voice and video communication session can beestablished from a web browser and by extension from an application, theexternal behavior of which is equivalent to that of a browser. Today, tostart a communication using WebRTC technology from a mobile telephone(typically a smartphone), the user must generally start a compatiblebrowser (e.g. Chrome) to target a particular URL (Uniform ResourceLocator, or web address), corresponding to the WebRTC service that theuser desires. The browser receives in response an HTML5 page (HTML5:HyperText Markup Language version 5, a format for representing webpages)encapsulating JavaScript code (a script programming language mainly usedin interactive webpages) enabling the user to enter the number to callor to select it from an address book hosted by the server or from anaddress book of the mobile or of the UICC card (UICC: UniversalIntegrated Circuit Card, also known as a SIM card, for SubscriberIdentity Module), if the code encapsulated in the HTML5 page providesfor it, and the mobile terminal allows it.

From an ergonomic viewpoint, this is not an optimal procedure since itrequires a double entry: entry of the URL and then entry of thetelephone number of the called party. It also requires the user to knowthe URL to be used, according to whether he/she desires these calls tobe handled by his/her mobile operator, for example via a gateway to theIMS (IP Multimedia System, a system enabling electronictelecommunications operators to provide fixed and mobile multimediaservices), or through a third-party service provider.

From a quality-of-service viewpoint, again this is not an optimalprocedure since it can lead the user to make use of a service which isnot that of his/her mobile operator, such that the user cannot benefitfrom the same services as if the call were made using the nativesoftware of a mobile terminal, whether this be an IMS client for a VoLTEcompatible terminal (VoLTE: Voice over LTE; LTE, Long Term Evolution, isthe name of the most recent evolution in the mobile telephony standards,also known as “4G”) or software for making calls in circuit mode.

One of the aims of the invention is to remedy these drawbacks of theprior art.

SUMMARY

The invention arrives at improving the situation using a method forestablishing a session between a first mobile terminal and a secondterminal, comprising the following steps implemented by the firstterminal:

-   -   a step for obtaining an identifier of a session server,    -   a step for transmitting a session request to the server, using        the identifier of the server,    -   a step for transmitting an identifier of the second terminal to        the server,    -   a step for receiving at least one instruction from the server,    -   a step for generating, according to the at least one received        instruction, a message containing a first set, relating to the        first terminal, of at least one characteristic parameter of the        requested session,    -   a step for transmitting the generated message to the server,    -   a step for receiving, from the server, a message containing a        second set of at least one characteristic parameter of the        requested session, the second set relating to the second        terminal and having a non-zero intersection with the first set,    -   a step for establishing the session between the first mobile        terminal and the second terminal, using the second set of        parameters, the identifier of the server being obtained at least        from a subscriber module for a mobile electronic communications        operator, included in the first terminal, the module containing        an identifier of a subscriber and an identifier of the operator.

In order to establish a WebRTC type communication, a first terminalconnects to a WebRTC server and receives an HTML or JavaScript codeform, which it uses to request a session with a second terminal. Forthis purpose, the first terminal uses a web browser exchanging HTTPrequests or SIP messages with the WebRTC server, for example.

The server processes the session request and transmits to the secondterminal a session request on behalf of the first terminal.

The session request transmitted by the first terminal contains a list ofsession parameters, for example a list of codecs which the firstterminal is capable of using. This list is transmitted by the server tothe second terminal.

If the second terminal accepts the session request transmitted by theserver on behalf of the first terminal, it responds according to asimilar process but in the other direction, indicating a subset ofsession parameters which it is capable of implementing, for example asub-list of codecs of the first terminal which it is capable of using.

Lastly, the session is established directly between the first and thesecond terminals, using session parameters common to both terminals,such as for example a common codec.

This procedure for establishing a session is possible only if the firstterminal is capable of obtaining the identifier of the correct WebRTCserver in order to connect to it.

Advantageously, by virtue of the method for establishing a sessionaccording to the invention, the selection of the WebRTC server isperformed by a subscriber module included in the first terminal, forexample a SIM card. This module contains, in addition to the subscriberand mobile operator identifiers, an identifier of the WebRTC server,which can be a partial or complete address of the server, for example inthe form of a URL. Users or subscribers no longer need to select aWebRTC server themselves, nor to enter the URL of this server in abrowser themselves. The WebRTC server is selected by their mobileoperator, in a manner optimally aligned with the characteristics of thenetwork managed by their mobile operator.

According to one aspect of the invention, the subscriber module is a SIMcard. The subscriber can thus change mobile terminal while continuing tobenefit from the advantages related to the invention, if he/she removesthe SIM card from the old terminal and inserts it into the new one.

According to one aspect of the invention, the session request containsthe identifier of the second terminal.

By virtue of this aspect, when the first terminal transmits an HTTPrequest to the WebRTC server, it can include in the URL an address ofthe second terminal, for example the telephone number, concatenated withthe partial or complete URL of the WebRTC server. Thus, there is onlyone request and it does not require the subscriber to enter, a secondtime, the number of the second terminal for another message intended forthe server.

According to one aspect of the invention, the method for establishing asession comprises a step for selecting the identifier of the secondterminal from an address book.

By virtue of this aspect, the identifier of the second terminal isselected by the user or subscriber from an ordinary address book, hostedlocally in the memory of his/her mobile terminal or of the SIM card, orfrom a remote database queried by a known method.

According to one aspect of the invention, the step for selecting theidentifier of the second terminal triggers the step for obtaining theidentifier of the server.

By virtue of this aspect, it is when the subscriber selects a contactfrom his/her usual address book that the session is automaticallyestablished using the WebRTC server, the address of which is containedin the SIM card of his/her terminal. Thus, everything proceeds for thesubscriber as if the call conveyed by the session were a call using theconventional mobile network of his/her operator, for example a VoLTEcall, and not a WebRTC call.

The subscriber therefore does not have to be concerned as to whether thecall must pass through the conventional network of his/her operator, aVoLTE network for example, or through the Internet via a WebRTC server,since the WebRTC server which is chosen by his/her operator by virtue ofthe invention is the one for which a quality of service closest to thatof a VoLTE call can be obtained.

The various aspects of the method for establishing a session which havejust been described can be implemented independently from one another orin combination with one another.

The invention relates also to a device for establishing a sessionbetween a first mobile terminal and a second terminal, comprising thefollowing modules:

-   -   a module for obtaining an identifier of a session server, at        least from a subscriber module for a mobile electronic        communications operator, included in the first terminal, the        module containing an identifier of a subscriber and an        identifier of the operator,    -   a module for transmitting a session request to the server, using        the identifier of the server,    -   a module for receiving at least one instruction from the server,    -   a module for generating, according to the at least one received        instruction, a message containing a first set, relating to the        first terminal, of at least one characteristic parameter of the        requested session,    -   a module for transmitting the generated message to the server,    -   a module for receiving, from the server, a message containing a        second set of at least one characteristic parameter of the        requested session, the second set relating to the second        terminal and having a non-zero intersection with the first set,    -   a module for establishing the session between the first mobile        terminal and the second terminal, using the second set of        parameters.

The device for establishing a session between a first mobile terminaland a second terminal is contained in a mobile terminal and is suitablefor implementing the method for establishing a session, which has justbeen described, in all its embodiments.

The transmission, generation, reception and establishment modules canform part of a web browser or a WebRTC-compatible dedicated application,installed on the mobile terminal. The obtaining module can form part ofan application installed on the SIM card of the mobile terminal.

The invention relates also to a mobile terminal comprising a device forestablishing a session between a first mobile terminal and a secondterminal, in accordance with that which has just been described.

The invention relates also to a computer program comprising instructionsfor implementing the steps of the method for establishing a sessionbetween a first mobile terminal and a second terminal which has justbeen described, when this program is executed by a processor.

Lastly, the invention relates to a recording medium that can be read bymanagement equipment, on which the program which has just been describedis recorded, able to use any programming language and be in the form ofsource code, object code or a code intermediate between source code andobject code, such as in a partially compiled form or in any otherdesirable form.

Advantageously, the program according to the invention can be installedeither in an executable form in the mobile terminal according to theinvention, or in a downloadable form on an application server separatefrom the terminal. In this latter case, the program can be downloadedfrom the application server to the terminal upon the initiative of theuser of the terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and features of the invention will become clearer uponreading the following description of a particular embodiment of theinvention, which embodiment is given by way of simple illustrative andnonlimiting example, and from the appended drawings in which:

FIG. 1 schematically presents an example implementation of the steps ofa method for establishing a session between a first mobile terminal anda second terminal, according to the invention,

FIG. 2 presents an example structure of a device for establishing asession between a first mobile terminal and a second terminal, accordingto one aspect of the invention.

DETAILED DESCRIPTION

Hereafter in the description, examples of several embodiments of theinvention are presented, based on the 3GPP LTE/EPC standard, but theinvention also applies to other former or later 3GPP standards, such asUMTS (Universal Mobile Telecommunications System, also known as 3G) or5G.

FIG. 1 schematically presents an example implementation of the steps ofa method for establishing a session between a first mobile terminal T1and a second terminal T2, according to the invention.

In this example, the user of a mobile terminal T1 calls the user ofanother terminal T2, for a voice or video communication with him/her bymeans of the terminals.

The terminal T1 is a mobile terminal including a subscriber module, i.e.a SIM card containing an identifier of a subscriber to a mobileelectronic communications operator, as well as an identifier of theoperator. With such a module, the terminal T1 can establish a“real-time” session to transport voice or video between this terminaland another terminal T2, using the resources of this operator or thoseof another operator having established roaming agreements therewith.This real-time session uses one or more codecs to change the voice/videofrom analog form to digital form and vice versa. The terminal T1 iscapable of using a set of codecs which is not necessarily the same asthat of T2. A negotiation must therefore have taken place between theterminals T1 and T2 in order to determine the codec or codecs to beused.

The terminal T1 is also suitable for establishing a WebRTC session, i.e.a communication session based for example on an SRTP, UDP and IPprotocol stack between two applications hosted by the terminals T1 andT2 respectively. These applications are typically called web browsers.The transport resources of the operator of T1, which are used for such asession, such as those of its LTE access network and of its EPC corenetwork, are determined by the choice of the WebRTC server which offersthe web service enabling the terminal T1 to establish a communicationsession with the terminal T2. It is therefore beneficial for theoperator to keep control over the establishment of the WebRTC session.

During a step E1, the user of the terminal T1 selects an identifier ofthe terminal T2, i.e. generally a telephone number, generally from anaddress book which can be local or remote. If it is local, it can behosted in the memory of the terminal or in that of the SIM card. If itis remote, the terminal T1 accesses it for example from a web browser ora dedicated application, according to a known procedure.

The expression “to select an identifier” in the sense of step E1 alsoincludes the case in which the user him/herself dials the telephonenumber of the terminal T2 if it is absent from the address book.

During a step E2, which can be triggered automatically by step E1, theterminal T1 obtains the identifier of a WebRTC server, that of theserver S, which must be used to establish the session with the terminalT2. Preferably, this identifier can be obtained from the SIM card of theterminal T1.

For example, “http://webrtc.orange.com” is a string of charactersrepresenting a URL address corresponding to the WebRTC server of anoperator called Orange, i.e. the server S. This string can be stored inSIM cards of mobile terminals managed by this operator in order to beread by the terminal during step E2.

This string can also be obtained by adding a predefined prefix,predefined by standards or by the operator when the mobile iscustomized, to the home network domain name featuring in the SIM card.

For example, if the domain name is “ims.orange.com” and the prefix is“webrtc”, the URL will be “http://webrtc.ims.orange.com”.

This string can even be obtained by adding a predefined prefix to thehome network domain name formed from a country code (MCC) and from anoperator network code (MNC), for example as specified in the standard3GPP TS 23.003.

For example, for the operator Orange, the URL can be:“http://webrtc.ims.mnc015.mcc234.3gppnetwork.com”.

During a step E3, the terminal T1 constructs an address containing boththe identifier of the server S obtained during step E2 and theidentifier of the terminal T2 selected during step E1. For example, ifthe identifier of the terminal T2 is the telephone number of the userassociated with the terminal T2, +33299124167, the constructed URL canbe: “http://webrtc.ims.orange.com/tel/0033299124167”.

During steps E4 and E5, the terminal T1 connects to the server S.

The terminal T1 transmits during step E4 a request for access to aWebRTC service offered by the server S, referred to as a session requestto the server S, in the form of an HTTP request using the URLconstructed during step E3. It is understood that in this embodiment ofthe invention, the session request to the server S contains theidentifier of the terminal T2.

The terminal T1 receives during step E5 an HTTP response from the serverS, containing instructions in the form of JavaScript code, for exampleencapsulated in an HTML5 page. These instructions enable the terminal T1to generate a message to be transmitted according to a protocol decidedupon by the WebRTC server and in a manner transparent to the terminal,and by retrieving information from the terminal such as for example theavailable codecs, and/or by retrieving certain audio/video streams fromthe microphone and/or from the camera, in order to be able to transmitthem to the outside.

During a step E6, the terminal T1 generates a session request to theterminal T2 according to the content of the JavaScript code receivedduring step E5. For example, if the protocol used by the WebRTC serviceprovider is SIP, a SIP over WebSocket message “INVITE tel:0033299124167SIP 2.0” can be generated by the terminal T1, if the JavaScript codecontains the identifier of T2. WebSocket is a protocol providing forobtaining a channel for simultaneous bidirectional communications abovethe TCP (Transmission Control Protocol) layer. This SIP message alsocontains the SDP (Session Description Protocol) offer of the terminalT1, i.e. a set of codecs that can be used by the terminal T1, and itsports and addresses for the media streams (voice, video, etc.).

Alternatively, if the WebRTC service provider does not use the SIPprotocol, an HTTP request can be generated during step E6, containingthe identifier of the terminal T2 and the codecs, addresses and ports ofT1.

If the JavaScript code received during step E5 does not contain theidentifier of the terminal T2, this identifier must be retrieved one wayor another by the terminal in order to be inserted into the HTTP requestgenerated during step E6. In that case, the HTML5 page will typicallyhave, in addition to the JavaScript code, a form to enter theidentifier, for example a telephone number.

Alternatively, protocols other than SIP or HTTP can be used. In thesecases, it is also the JavaScript code instructions which will indicateto the browser of the terminal T1 how to generate the session request,and in how many messages.

During a step E7, the session request generated during step E6 istransmitted by the terminal T1 to the server S.

During a step F1, the server S receives this request.

During a step F2, the server S transmits to the terminal T2 an identicalor equivalent request, containing the same information as the requesttransmitted by the terminal T1 during step E7. There can be one or moreintermediate servers between the server S and the terminal T2. Theprotocol or protocols used between the server S and the terminal T2 canalso differ from that or those used between the server S and theterminal T1, if they allow a negotiation of the SDP offer between theterminals T1 and T2.

During a step F3, the terminal T2 transmits in response to the server Sa session request to T1, containing an SDP answer, i.e. a subset of thecodecs proposed by the terminal T1, or their equivalent. This subsetcontains the codecs proposed by the terminal T1 which the terminal T2 iscapable of using.

During a step F4, the server S transmits to the terminal T1 an identicalor equivalent request, containing the same information as the requesttransmitted by the terminal T2 during step F3.

During a step E8, the terminal T1 receives the session request of theterminal T2. This request can take the form of a “180 Ringing” or “200OK” SIP message, containing the SDP answer, i.e. the subset of thecodecs proposed by the terminal T1 which the terminal T2 is capable ofusing, as well as an address and a port on which the terminal T2 expectsthe media streams transmitted by the terminal T1.

Lastly, during a step E9, the communication session between theterminals T1 and T2 is established using one or more of the codecscompatible with the terminal T2.

In an alternative embodiment, step E3 is replaced by a step G3 (notillustrated) for constructing an address containing the identifier ofthe server S and one or more possible prefixes, but not the identifierof the terminal T2. This provides for covering the case in which theuser him/herself dials a number which is not in his/her address book.

Step E4 is replaced by a step G4 (not illustrated) for transmitting asession request to the server S, but in which the session request to theserver S does not contain the identifier of the terminal T2.

Step E1 for selecting the identifier of the terminal T2 can be replacedby a step G1 (not illustrated) for obtaining the identifier of theterminal T2, for example by the user dialing the number. Step E1, orstep G1, can in this embodiment take place after step E2 for obtainingthe identifier of the server S.

Step E6 then awaits completion of step E1, or step G1, and it is onlyduring step E7 for transmitting the session request when the identifierof the terminal T2 is transmitted.

With reference to FIG. 2 , there is now presented an example structureof a device for establishing a session between a first mobile terminaland a second terminal, according one aspect of the invention.

The device 100 implements the method for establishing a session betweena first mobile terminal and a second terminal, various embodiments ofwhich have just been described.

Such a device 100 can be implemented in a mobile terminal suitable forestablishing an IP connection with a node of an access network, conveyedby a radio connection.

For example, the device 100 comprises a processing unit 130, equippedfor example with a microprocessor μP, and driven by a computer program110 stored in a memory 120 and implementing the method for establishinga session between a first mobile terminal and a second terminalaccording to the invention. Upon initialization, the code instructionsof the computer program 110 are for example loaded into a RAM memorybefore being executed by the processor of the processing unit 130.

Such a device 100 comprises:

-   -   a selection module 141, suitable for selecting an identifier of        a remote terminal from an address book C,    -   an obtaining module 142, suitable for obtaining an identifier of        a WebRTC server from a subscriber module SIM, or SIM card,    -   a construction module 143, suitable for constructing an        identifier, such as for example a URL address, by combining the        identifier of the selected remote terminal, the identifier of        the WebRTC server and if necessary another identifier such as a        predetermined prefix,    -   a transmission module 151, suitable for transmitting a session        request to a WebRTC server, in the form of an HTTP request        containing the constructed URL address,    -   a reception module 152, suitable for receiving an instruction        from the WebRTC server, for example an HTTP response,    -   a generation module 153, suitable for generating a session        request to the remote terminal based on the instruction received        from the WebRTC server, for example in the form of an SIP        message or an HTTP request containing an SDP offer,    -   a transmission module 154, suitable for transmitting the        generated session request to the WebRTC server,    -   a reception module 155, suitable for receiving from the WebRTC        server a session request on behalf of the selected remote        terminal, for example in the form of an SIP message or an HTTP        response containing an SDP answer,    -   an establishment module 156, suitable for establishing a WebRTC        session with the selected remote terminal, for example using        information contained in the received SDP answer.

The modules 141, 142 and 143 can be included in a first application APP1running on the SIM card of the mobile terminal implementing the device100. The address book C can be stored in the SIM card, in a memory ofthe mobile terminal outside the SIM card or in separate equipmentoutside the mobile terminal, accessible using a dedicated application.The application APP1 can also run on the mobile terminal outside the SIMcard. This application APP1 can be pre-installed by the manufacturer ofthe mobile or the operator, or installed by the subscriber bydownloading from an Internet site such as for example an app store.

The modules 151 to 156 can be included in a second application APP2acting as WebRTC client. This application APP2 can be aWebRTC-compatible browser running on the mobile terminal, such asChrome, Firefox, Opera, Internet Explorer, Safari, etc. or a dedicatedWebRTC-compatible application able to be executed outside the browserand installed on the mobile terminal. This application APP2 can bepre-installed by the manufacturer of the mobile or the operator, orinstalled by the subscriber by downloading from an Internet site such asfor example an app store.

The modules described with reference to FIG. 2 can be hardware orsoftware modules.

By virtue of the device for establishing a session between a firstmobile terminal and a second terminal according to the invention,several ergonomic features are possible for establishing a call inWebRTC mode, in particular:

-   -   either the application APP1 is started from the address book C        by selecting therein an identifier, or contact, and by pressing        on an icon or a key of the mobile terminal to start the        application APP2 and thus establish the session, i.e. the call,    -   or the application APP1 is started from the home screen of the        mobile terminal, by pressing on a key or an icon to open the        address book C, select a contact in it, start the application        APP2 and thus establish the session, i.e. the call.

The application APP1 is associated with an icon or a key of the mobileterminal when the application APP1 is initialized, for example when theterminal is put into operation with the SIM card inserted, according toa method which depends on the terminal and on the operating system used.

The example embodiments of the invention which have just been presentedare only some of the conceivable embodiments. They show that theinvention enables a subscriber to a mobile telecommunication service tobenefit from the WebRTC service best adapted to the network of his/heroperator, in a manner transparent to him/her, simply by selecting orentering the telephone number of his/her correspondent on his/her mobileterminal.

What is claimed is:
 1. A method for establishing a session between afirst mobile terminal and a second terminal, comprising the followingprocesses implemented by the first terminal: obtaining, from asubscriber identity module managed by a mobile communication operator,an address of a server for managing a request for access to a WebReal-Time Communication (WebRTC) service, the subscriber identity modulecontaining an identifier of a subscriber and an identifier of theoperator, the address being represented by a string of characters storedin the subscriber identity module; transmitting a request for access toa WebRTC service to the server for managing a request for access to aWebRTC service, using the obtained address of the server; receiving atleast one instruction from the server for managing a request for accessto a WebRTC service; generating, according to the at least one receivedinstruction, a session request containing a first set, relating to thefirst terminal, of at least one characteristic parameter of therequested session; transmitting the generated session request to aserver for processing a session request; receiving, from the server forprocessing a session request, a message containing a second set of atleast one characteristic parameter of the requested session, the secondset of at least one characteristic parameter relating to the secondterminal and having a non-zero intersection with the first set; andestablishing the session between the first mobile terminal and thesecond terminal, at least using the second set of at least onecharacteristic parameter.
 2. The method of claim 1, wherein obtainingthe address of the server for managing a request for access to a WebRTCservice comprises reading by the first terminal the string of charactersstored in the subscriber identity module.
 3. The method of claim 2,wherein the address of the server for managing a request for access to aWebRTC service is a URL address.
 4. The method of claim 3, wherein thestring of characters representing the URL address of the server formanaging a request for access to a WebRTC service comprises a prefixdesignating the server for managing a request for access to a WebRTCservice and a home network domain name.
 5. The method of claim 1,wherein the at least one instruction is in the form of Javascript code.6. The method of claim 1, wherein the request for access to a WebRTCservice is a HTTP request, the at least one instruction being receivedby the first terminal in a HTPP response.
 7. The method of claim 1,wherein the server for managing a request for access to a WebRTC serviceand/or the server for processing a session request is a WebRTC server.8. A device for establishing a session between a first mobile terminaland a second terminal, the device comprising a processor and a memory,the device configured to: obtain, from a subscriber identity modulemanaged by a mobile communication operator, an address of a server formanaging a request for access to a Web Real-Time Communication (WebRTC)service, the subscriber identity module containing an identifier of asubscriber and an identifier of the operator, the address beingrepresented by a string of characters stored in the subscriber identitymodule; transmit a request for access to a WebRTC service to the serverfor managing a request for access to a WebRTC service, using theobtained address of the server; receive at least one instruction fromthe server for managing a request for access to a WebRTC service;generate, according to the at least one received instruction, a sessionrequest containing a first set, relating to the first terminal, of atleast one characteristic parameter of the requested session; transmitthe generated session request to a server for processing a sessionrequest; receive, from the server for processing a session request, amessage containing a second set of at least one characteristic parameterof the requested session, the second set of at least one characteristicparameter relating to the second terminal and having a non-zerointersection with the first set; and establish the session between thefirst mobile terminal and the second terminal, at least using the secondset of parameter.
 9. The device of claim 8, wherein the device isfurther configured to read the string of characters stored in thesubscriber identity module in order to obtain the address of the serverfor managing a request for access to a WebRTC service.
 10. The device ofclaim 9, wherein the address of the server for managing a request foraccess to a WebRTC service is a URL address.
 11. The device of claim 10,wherein the string of characters representing the URL address of theserver for managing a request for access to a WebRTC service comprises aprefix designating the server for managing a request for access to aWebRTC service and a home network domain name.
 12. The device of claim8, wherein the at least one instruction is in the form of Javascriptcode.
 13. The device of claim 8, wherein the request for access to aWebRTC service is a HTTP request, the at least one instruction beingreceived by the first terminal in a HTPP response.
 14. The device ofclaim 8, wherein the server for managing a request for access to aWebRTC service and/or the server for processing a session request is aWebRTC server.
 15. A non-transitory computer readable medium havingstored thereon instructions which when executed by a processor, cause amobile terminal to perform a method for establishing a session between afirst mobile terminal and a second terminal, wherein the methodcomprises: obtaining, from a subscriber identity module managed by amobile communication operator, an address of a server for managing arequest for access to a Web Real-Time Communication (WebRTC) service,the subscriber identity module containing an identifier of a subscriberand an identifier of the operator, the address being represented by astring of characters stored in the subscriber identity module;transmitting a request for access to a WebRTC service to the server formanaging a request for access to a WebRTC service, using the obtainedaddress of the server; receiving at least one instruction from theserver for managing a request for access to a WebRTC service;generating, according to the at least one received instruction, asession request containing a first set, relating to the first terminal,of at least one characteristic parameter of the requested session;transmitting the generated session request to a server for processing asession request; receiving, from the server for processing a sessionrequest, a message containing a second set of at least onecharacteristic parameter of the requested session, the second set of atleast one characteristic parameter relating to the second terminal andhaving a non-zero intersection with the first set; and establishing thesession between the first mobile terminal and the second terminal, atleast using the second set of at least one characteristic parameter. 16.The non-transitory computer readable medium of claim 15, whereinobtaining the address of the server for managing a request for access toa WebRTC service comprises reading by the first terminal the string ofcharacters stored in the subscriber identity module.
 17. Thenon-transitory computer readable medium of claim 16, wherein the addressof the server for managing a request for access to a WebRTC service is aURL address.
 18. The non-transitory computer readable medium of claim17, wherein the string of characters representing the URL address of theserver for managing a request for access to a WebRTC service comprises aprefix designating the server for managing a request for access to aWebRTC service and a home network domain name.
 19. The non-transitorycomputer readable medium of claim 15, wherein the at least oneinstruction is in the form of Javascript code.
 20. The non-transitorycomputer readable medium of claim 15, wherein the server for managing arequest for access to a WebRTC service and/or the server for processinga session request is a WebRTC server.